Radial drill with all change gears centralized in head



Feb. 1l, 1930. D. c. KLAUSMEYER RADIAL DRILL WITH ALL CHANGE GARSlGENTRALIZEDIN HEAD She'ets-Sheet 1 original' Filed Feb. i9. 124

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Feb. 11,1930. f D. c. KLAusMEYrRY v1,745,703

RADIAL DRILL WITH ALL CHANGE GARS CENTRALIZED IN HEADor1g1na1'F11ed.Feb.19. 1924 5 sheets-sheet -2 @aw/l SZW Quo/maa [wwwFeb. l1,y 1930. D. cl KLAuslvllaYrftR RADIAL DRILL WITH ALL CHANGE GEARSCENTRALIZED IN :s sneewsueet s origmal Filed Fem-'19. 1924 I Nw l Wart/fPatented Feb. 11, 1930 UNITED STATESy PATENT OFFICE DAVID C. KLAUSMEYER,OF CINCINNATI, OHIO, ASSIGNOR T THE CINCINNATI .'BICK-v FORD TOOLCOMPANY, OIF CINCINNATI, OHIO,-A..CORPORATION 0F OHIO RADIAL DRILL WITHALL CHANGE GEARS CENTRALIZED H EAD Application led Tebruary 19, 1924,Serial No. 693,945. Renewed February 12, 1926c This invention relates toradial drilling and tapping machines and more particularly to the speedcontrollingmechanism for the spindles thereof.

Machine tools of this character are usually constructed with a base, anupright column, and a laterally projecting arm upon which Y i thedrill-head is adjustably mounted. Power to rotate the drill spindle andto feed it vertically is usually provided by a motor or otherprime-mover located on the base at the foot `of the colummand thev powertherefrom is transmitted through suitable mechanism to 'a shaftjournaled lengthwise of the radial arm and Vthence through suitablechange-gear mechanism to the ldrill spindle.

As is well, understood by.those skilled in the art, it is essential thatmeans be provided for regulatin the speed of rotation of the drillspindle inasmuch as the varying diameters of the drills-and taps and thenature of the work being operatedon, each present working-condit1onswhich require diii'erent speeds of rotation of the spindle to producemaximum efiiciency in operation.

To provide these various speeds it has heretofore been customary tolocate, adjacent the prime-mover# a change-gear mechanism ca pable oftransmitting about six different speeds from a single speed receivedfrom the 'prime-mover.l The differences in ratio aiforded by thisso-Called speed-box control are necessarily small since there isconsiderable mechanism actuated thereby and great differences in ratioWould effect abrupt changes andcause strains that would be detrimentalto the parts.

Coarser changes are provided by a changegear mechanism located in thedrill-head. These latterchangegears are known as the backgears andusually provide four speed changes which multiply the speeds provided bythe speed-.bex into about4v twenty-four speeds in the spindle. inasmuchas only the spindle is actuated by the back-gears the speed changesprovided therein may be materially greater than those provided in thespeed boX.

Another Well-known way of providing the in necessary number of spindlespeeds is to replace the single-speed `prime-mover and the speed-boxwith a variable speed motor capaltherewith the usual back-gears in thedrill` head.

To effect a predetermined speed in the spindle it has heretofore beennecessary for the operator first, by the manipulation of certain controllevers carried; by the drill-head, to shift the back-gears and therebobtain the nearest approximate speed obtainable therein l; and second,to leave his position at his work and go to the opposite end of themachine Where, by the manipulation of the speed-box control lever, orthe motor controller Whichever the case may be, eect the `liner and moreaccurate speed setting, This remote location of the finer change-gearsmakes their frequent manipulationinconvenient and unhandy and thereforethe tendency of the attendant is to ignore the finer speed settings andto rely on the nearest speed obtainable in the back-gears which he mayshift from his position at his work which necessarily reduceseiiiciencye This invention has for an object to combine entirely Withinthe drill head, a plurality'of sets of speed changing Vdevices operativein conjunction with the usual back-gears to pro duce twenty-'four speedsin they spindle from a single speed in the drive shaft.

A further object of the invention is to provide an improved forni ofgear shifting mechanism for selectively engaging the gears of thespeed-change mechanisms.

A still further object is to provide improved means Jfor maintaining thegears in their adjusted positions.

Another object of this invention is so to arrange theV gears of theinitial speed change. device that, by simple movements of the shiftingiever, the gears may be meshed in apredeterminedorder tol progressivelyincrease or decrease the speed, whereby each speed attained will be onlyslightly greater or less than the preceding speed, thus precluding theclashing of fast and slow running gears,-

Still another object of this inventiongis so to` arrange, in the drillhead, the change gear sets for producin the twenty-four s eeds from asingle spee prime-mover, that, 1f desired, the initial speed chan egears may be eliminated and the drill-hea may readily be converted foruse in conjunctionwith a variable speed motor and the back-gears onlyand still j obtain the same results as is obtained with the single speedmotor, the speed-box, and the back-gears.

These and other objects are attained b combining in the'drill-head threeindepen ent speed-change devices of which the first tworovide six speedchanges and corres n to the usual speed-boxcontrol, and the t ird, whichis the usual .back-gears, rovides l four speed-changes, thus provi ingtwenty-four speed-changes in the spindle.

A single control lever is provided for shifting the gears of the firstand second gear-sets. This lever is mounted so as to be capable ofuniversal movements and is so connected with the shiftable unit of eachset that a movement in a vertical plane will shift the gears of one setand a movement in a'horizontal plane will shift the gears of the otherset. Independent shiftin levers are provided for the shiftable units o`the back-gears. Spring detents are` arran ed to engage the gearshifting devices where y the levers, and thereby the gearunits, are heldin `adjusted positions.

To provide for the use of either a constant s eed motor or a variablespeed motor, the s aft supporting the driving gear-unit of the rstgear-set is arranged co-axially with the shaft supporting the drivingear ofthe backgear set so that,.when desire a single shaft may beinserted in place of the two independent shafts and the back gears thusconnected directly with the drive shaft. With this arrangement the firstand second gear-sets are eliminated, the variable speed motor providingthe initial speed-chan es. This is a highly important and desirab efeature from the standpoint of manufacture as it permits the machinetool to be constructed completely with the exce tion of the motor andthe chan e-gear evices, either form of which may supplied later to meetthe varying demands of the trade.

Other objects and advantages will be in part indicated in the followingdescription and in part rendered apparent therefrom in connection withthe annexed drawings.

To enable others skilled in the art so fully to apjlrehend the underlingfeatures hereof that t ey may embody t e same in the various wayscontemplated by this invention, drawings depicting a preferred typicalconstruction have been annexed as a art of this disclosure and, in suchdrawings, like characv ters of reference denote corresponding partsthroughout all the views, of wh1ch:

Fig. 1 is a vertical section of a drill-head embodying the presentinvention. Fig. 2 is a detail section substantially on the line 2-2 ofFig. l but showing certain parts thereabove in elevation. Fig. 3 is aleft-end view of Fig. 2. Fig. 4 is a diagrammatic representation of theflow of motion throu h the speed change mechanism. Fig. 5 is a etailview of detent means, later to be referred to, for holding the gearunits in adjusted positions. Fig. 6 is a View similar to Fig. 1 butshowing the drillhead equipped for use in conjunction with a variablespeed motor. Fig. 7 is a detail section showing a modified arrangementof certain of the gears of the initial speed-change mechanism'. Fig. 8is a detail view of the speed index as used in conjunction .with thegear arrangement shown in Fig. 7.

Referring more particularly to the'drawings, especially to Figs. 1 and4, power from a prime-mover, which may be a single speed motor, is(through suitable mechanism not shown) transmitted to a shaft 1journaled lengthwise of the usual radial arm. From the shaft 1 the powerflows to an upright shaft a journaled, by means of anti-frictionbearings in bearing bosses 1 and 1, in the drill head L, suitablebevelgears represented generally by m serving to operatively connect the twoshafts. Either of two bevel gearson the shaft l (one only of which isshown) may be meshed with the bevel gear on the shaft a to .drive theshaft in reverse directions, but as this feature forms no part of theresent inventon detailed illustration and escription thereof is deemedunnecessary.

Upon the shaft a is splined a gear unit 2 providing gears A, B and Cadapted to mesh respectively with gears A', B and C comprising agear-unit 3, loosely journaled on a shaft b fixed within bosses 1b inthe drill head, parallel with the shaft a. These gear-units 2 and 3constitute afirst speed-change device X (seeEig. 4) which provides threespeeds from a single speed shaft 1 (hereinafter termed the power-shaft).A gear-unit 4 is also loosely journaled on the shaft b and is clutchedat 5 to turn-with the gear-unit 3. rlhe gear-unit 4 provides gears Dand'E adapted to mesh respectively with gears D and E formed on ashiftable gear-unit'. These ear-units 4 and 6 constitute a secondspeed-c ange device Y which doubles the three speeds available in theunit 3. The gear-unit 6 is splined upon a shaft c journaled co-axiallywith the shaft a in bearing bosses 1 and 1i in the drill head.

IThese shafts a and c being arranged co-axially may be replaced by asingle shaft as will later be explained.

Splined upon the shaft c is a gear unit 7 constitutin the first of ayseries of gears Z commonly own as the back-gears which, operativelconnects the six vspeed shaft c with the rill-spindle and multiplies itssix speeds four-fold, thus providing twenty-four spindle speeds. Thegear-unit 7 comprises gears F and G adapted selectively to be shiftedinto meshQwith gears F and'G, respectively, provided bn a gear-unit 8,keyed to a shaft d, journale at one end in ya bearing 1c in thedrill-head and at the other end in a bearing s formed co-axially in theshaft b. The driven gear F also acts as a driver and meshes with a gearH provided by a gearunit 9 splined upon a sleeve 10, which in turn issplined to the drill spindle 11 in the usual manner. The shaft d isprovided with a pinion I maintained constantly in mesh'with a large gearI forming a part of a gear-unit 12 loosely j ournaled upon the sleeveand provided with an internal gear H. The gearf unit 12 may beoperatively connected with the spindle-sleeve by shifting the gearA Hdownwardly into mesh with the internal gear H.

The gear-units 2 and6 are adapted to be u shifted lengthwise of theirsupporting shafts to engage the gear-units 3 and 4 respectively, by asin le mechanism now to be described.

- Within earings 13 and 14, provided by the drill head, is slidably androtatably mounted a shaft 15 upon whlch is secured a rack 16. Agear-shifting member 17, in the form of a bell crank lever, is pivotedat 18 in the drill head and carires at one end a shoe 19 adapted totrack an annular groove 2() in the unit 6. The opposite arm of thebell-crank is formed as a gear-segment which meshes with the rack 16.Thus it will be seen that endwise movement of the shaft 15 will, throughthe rack 16, bell-crank lever 17, and shoe 19, shift -5 the gear-unit 6lengthwise of the shaft c..

, Upon a bushing, journaled within the bearing 14 and keyed to the shaft15, is secured the hub of an arm 21 which carries a shoe 22 adapted toengage an annular groove 23 formed inthe gear-unit 2. This arm 21`isformed with an arcuate sector 24 provided with a. plurality ofindentations i which cooperate with a spring pressed detent plunger 25slidably mounted in the frame of the drillhead to maintain the anni 21and the gearunit 2 in adjusted position. Means to rotate the shaft 15 toshift the gear-unit 2, and to move it endwise to shift the gear-unit 6,preferably comprises a hand-lever 26 pivoted at 27 to the shaft, andcarrying intermediate its ends a roller 28 which, when the lever isvmoved vertically slides between walls 'w provided by a bearing bracket29 supported by the drill-head. r

5 Upon movement of the hand lever 26 hori zontally the walls lw hold theroller 28 against movement and the lever fulcrums about thel the planesin which the finger o moves in either of the two lengthwise adjustedpositions of the shaft 15. Thus the operator may,

by manipulating the hand-lever 26, shift the gear-sets X and to secureany one of the six speeds indicated by the indexes m and n. Thegear-units 7 and 9 are adapted to be shifted `by rock-arms 31 and 32respectively Y secured upon pins 33 and 34 secured in the frame of thedrill head. These arms engage the gear-units 7 and 9 in a well-knownmanner and suitable actuating levers (not shown) are secured to theshafts 33 and 34 outside of The bell-crank lever 17 and the arms 31 and32 are'each provided at its outer end with a sector g `within lwhich isformed indentations c which cooperate with spring pressed detents 35slidingly fitted within cavities 36 provided by the drill-head frame. Asthese sectors and detents are all similar only one is shown in detail(see Fig. 6).

For certain purposes it may be desirable to have the gears ofthe initialgear set arranged as illustrated in Fig. 7. vWith this arrangement thehighest speed is obtained by shifting the lever 26 to its uppermostposition and then shifting it horizontally to move the shaft 15inwardly. This will connect the gears C--C and E--E thus effecting al-to-l Vdrive between the shaft aI and the shaft c, all connected gearsbeing equal. In this position the indicator finger o will be in theposition 1 on Fig. 8, this representing the highest speed obtainable inthe first two ear-sets. Thenext lower speed is obtained gy moving thelever horizontallyto move the shaft 15 to the left as viewed in- Fig. 1.This movement causes the rack 16 to swing the bell-crank and shift thegear D into mesh with the gear D, the indicator finger having been movedoutwardly to the numeral 2 on the index m. Alternate vertical andhorizontal movements of the lever 26 wilLproduce a gradual decrease ofspeed until the position 6 (Fig. 8) is reached in which the gears A-.Aand D-D are in' mesh thusproducing the lowest speed drive betweenthefshaft a and the shaft c.

Referring now to Fig. 6 the drill`head is a single shaft 40 replaces theshafts a, b and cx and the gear-sets X and Y and connects the 1 powershaft 1 with the rst of the back-gears. This shaft 40 is journaled atits upper end in the bearing 1d provided by the drill-head frame-and atits lower end in an anti-friction bearing fitted in the bearing-boss 1f;passing centrally through the bearing boss 1a which in' this arrangementperforms no function. Inasmuch vas the initial s eed changes areeffected by a variable spee motor; connected v be journaled at its lowerwith the shaft 1 the shaft b and gear-units 3, 4 and 6 may be omittedand the shaft d may end in a bushing 41 carried by the bearin boss 1".Likewise the shiftin means for t e gear-units 2 and 6 may be e iminated.

The co-axial arrangement of the bearings for the pairs of shafts is ofgreat importance as it permits, first, a compact arrangement, in alimited space, of a plurality of gear sets capable of producingtwenty-four spindle speeds and second, it permits the same frame to befitted, without change with the alterc nate arrangement shown in Fi 6and therefore the manufacturer may, wit out added expense produce adrill head which he may later t in either of two different ways to meetthe varying demands of the trade.

Without further analysis, the foregoing will so fully reveal the 1st ofthis invention that others can by ap ying current knowledge,l readily aapt it or various utilizations by retaining one or more of the featuresthat, from the standpoint'of the prior art, fairly constitute essentialcharacteristics of either the generic or s ecific aspects of thisinvention, and, there ore, such adaptations should and are intended tobe, comprehended within the meanin and rangeof equivalency of thefollowing c aims.

Having thus revealed this invention, I claim as new and desire to securethe following combinations and elements, or e uivalents thereof, byLetters Patent of the nited States:

1. A drilling machine combining a drillhead; a ower shaft; a sleevejournaled in -said dril head; a spindle splined to saidl sleeve; asecond shaft journaled in said drillhead and operatively connected withsaid power shaft; speed-change mechanism carried within said drill-headfor operatively connecting said second shaft with said sleeve, saidmechanism including a third shaft secured in said drill-,head arallelwith said second shaft, a fourthsha journaled in said drill-headco-axially with said second shaft, a fifth shaft journaled within saiddrill-head co-axially with said third shaft, a chan egear set carried bysaid second and third shafts, a second change-gear set carried by saidthird and )fourth shafts and operatively connecte/d with said first gearset, and a backgear set operatively connecting said fourth shaft withsaid sleeve, said back-gear set comprising gear-units securedupon saidfourth and fifth shafts and said sleeve; and means for meshin the gearsof said gear-sets.`

2, A dril ing machine combining a. drillhead; a power shaft; a secondshaft journaled in said drill-head.y and operatively connected with saidpower shaft; a first gearunit shiftably secured to said second shaft;

a third shaft carried by said drill-head parallel with said secondshaft; a second earunit loosely, journaled on said third s aft,

said first'an'd second gear-units together constituting a firstspeed-change device providing three speed changes; a third gear-unitloosely-journaled on said third shaft and clutched to saidsecond-gear-unit; a fourth shaft journaled yco-axially with said secondshaft; a fourth gear-unit shiftably secured upon said fourth shaft andadapted to be meshed with said third gear-unit, said third and fourthgear-unitsO constituting a second speed-change device for doubling thespeeds received from the first speed-change device;

a fifth shaft journaled co-axially with said to said second shaft; athird shaft parallel.

with said second shaft; a fourth shaft parallel with said third shaft;afirst gear-unit journaled on said third shaft and adapted to mesh withthe gear-unit on said second shaft; a second gear-unit journaled on saidthird shaft and clutched to said first gear-unit thereon; a gear-unitshiftably secured to said fourth shaft and adapted to be meshed with thesecond gear-unit on said third shaft; a`

spindle journaled in said drill-head; operative connections between saidspindle and said fourth shaft for rotating the former from the latter;and a sin le gear-shifting lever carried by said drillead andoperatively connected to the gear-units on said second and fourth shaftsfor selectively shifting the gearsthereof into mesh with the gears ofthe first and second gear-units on the third shaft.

4. A drilling machine combining a drillhead, a power shaft; a spindlerotatably journaled in said drill-head; means for rotating said spindlefrom said power shaft at varying speeds, said means including aplurality of shafts and first, second, and third change-gear deviceseach including a shiftable and a non-shiftable gear-unit; a singleshifting mechanism for shifting the gears of said first and secondchange-gear devices, said shifting mechanism comprising a slideshafttranslatably and rotatably journaled in said drill-head; a rack securedto said shaft;

a gear shifting bell-crank lever fulcrumed on a pin secured in thedrill-head and having one arm provided with a gear-segment engaging saidrack and the other arm provided with a fork engaging the shiftablegear-unit of said second change-gear device; anfarm splined to saidslide-shaft; a fork carried by said arm and engaging the shiftablegear-unit on the second shaft; and a hand-'lever secured to said slideshaft and movable in a vertical plane to rotate said shaft to shift oneof said gear-units and in a horizontal plane to shift another of saidgear-units. i

5. The combination set 'forth in claim 4 characterized` by thisr the armof the gearshifting bell-crank lever that is connected with the slidinggear-unit on the fourth shaft and the arm splined to the slide-shaft andcarrying a fork engaging the sliding gearunit of the second shaft, areeach provided with a segmental extension containing'a plurality ofidentations which cooperate with av spring detent slidingly mounted inthe drillhead frame to maintain the gear-shifting y arms and thereby thegear-units in their adnjusted positions.

6. A drilling machine, combining a drill head; a power shaft; a spindle;means for rotating said spindle from said power shaft; a plurality ofspeedchange devices for regulating the speed of rotation of said spindleeach comprising a shiftable gear-unit and a non-shiftable gear-unitprovided with gears of varying diameters; means for shifting saidtranslatable gear-units comprising a rotatable slide-shaft; a singlehand-lever connectedwith said shaft for rotating the shaft and slidingit endwise; means actuated by the rotary motion for shifting one of saidl gear-units; means actuated by the sliding movement of said shaft forshifting another l of said gear-units an indicator finger carried bysaid slide-shaft; an index cooperating with the linger in each of thelengthwisev adjusted positions of said slide-shaft, said indexes eachcomprising indicia designating thespeed obtained in any adjustedposition of the hand-lever.

ings formed'in said frame and arranged with their axes parallel with theaxes of said first series; a shaft removably secured in two ofthe lastnamed series; a bearing formed coaxially in said last mentioned shaft; ashaft journaled at one end in the bearing in said shaft and at its otherpend in the third bearing of said second series; a sleevejouranled inthe frame; a spindle splined 1n said sleeve;

' intermeshing speed-change gear-units carried by said lsleeve and saidshafts for operatively connecting said spindle with said power shaft;and means for selectively shifty. ing certain of said gear-units.

8. A drill-head combining a casing; a

power shaftstwo shafts journaled "eo-axially in said casing with theiraxes intersecting the axis of sald power shaft; a driving connectionbetween one of said shafts and said power shaft; a non-rotatable shaftsecuredin said casing parallel with said two coaxially arranged shafts;two speed-change devices operatively connecting one of said twoco-axially arranged shafts with the other, said speed change devicescomprising two connected gear-units ldosel journaled on saidnon-rotatable shaft an a gear-unit on eachof said two shafts adapted tobe meshed with one of said two connected gear-units; a spindle journaledin said casing; a back-gear mechanism operatively connecting saidspindle with said two speed change-devices; and

means permitting the removal of said two coi change gears embodied insaid drill-head to rotate said spindle at a plurality of speeds from asingle speed in the power shaft; shafts upon which said gears aremounted; bearings in said drill head rotatably to support said shafts,said bearin s, gears and shafts being arranged on only t ree parallelaxes.

,i 10. A drilling machine combining a drillhead; a power shaft; a secondshaft journaled in said drill head and operatively connected with saidpower shaft; a third shaft parallel with said second shaft; athree-speed changegear mechanism between said second and third shafts togive to said third shaft three speeds from a single speed in the powershaft;

a fourth shaft co-axial with the second shaft; a two-speed change-gearmechanism between the third and fourth shafts togive to said fourthshaft six speeds from a single speed in the power shaft; a spindlerotatably journaled in said drill head: and a four-speed change-gearmechanism between the fourth shaft and the spinde to give to saidspindle any one of twenty-four speeds., i

11. A radial drill jhead comprising a casing: a spindle journaledtherein; a power shaft; a plurality of vertically aligned bearing bossesformed integral with said casing; a set of back-gears operativelyconnected with said spindle; a plurality of shafts removably -iournaledi in bearings provided by said bosses; a gear connection between one ofsaid shafts and the power'sh'aft, said gear connection including adriving bevel gear on the power shaft and a complemental driven bevelgear journaled in said casing and held therein against axial movement,said driven bevel gear also having a splined connection with one of saidplurality of shafts; a plurality of speed change devices carried by saidplurality of shafts for delivering to said backgears a plurality ofspeeds to be multiplied by said back-gears; and means permittin theremoval of said plurality of shafts and speed change devices and thesubstitution therefor of a single shaft for directly connecting saiddriven bevel gear with the first gear-unit of said back gears.

12. A drilling machine combining a drillhead; a power shaft; three setso bearing bosses formed in said drill head and arranged on threeparallel vertical axes, of which one axis intersects the axis of saidpower shaft; a spindle rotatably journaled co-axial with one of saidsets of bearings; a plurality of aligned shafts'journaled in each of theother of said sets of bearings; a gear connection between one of saidshafts and said ower shaft; a plurality of sets of speed c ange gearscarried by said shafts and operatively connecting said power shaft withsaid spindle; and means to mesh the gears of each set selectively togive to the spindle any one of a plurality of speeds from a single speedin the power shaft. 13. A radialdrill-head comprising a casing; aspindle journaled therein; a power shaft; a gear on said power shaft; acomplemental gear rotatably journaled in a bearing provided by thecasing and driven by the first mentioned gear; a plurality of bearingsprovided by said casing; a set of back-gears within said casing andoperatively lconnected with said spindle; and means permitting said headto be equipped with a plurality of speed change devices for operativelyconnecting the driven gear with said back-gears, said means 1ncluding aplurality of shafts journaled in said bearings and change gears carriedby said shafts, or to be equipped with a single shaft journaled in onlycertain ones of said arings and directly connecting said driven gearwith said back gears.

14. In a radial drill-head, in combination a rotatable spindle; apower-shaft; an operative connection between said power-shaft and saidspindle including a pluralit of change-gear devices each including a siftable gear-unit; a single shifting mechanism for two of saidgear-units, said shiftin mechanism comprisin a shaft rotatably antranslatably journale in said head; a gear shifter engagmgbeach of saidtwo gear-units;

means actuated y the rotation of said shaft to actuate one of said gearShifters; means actuated by the axial movement of said shaft to actuatethe other of said gear Shifters; and a universally actuable leverconnected to said shaft and having a floating fulcrum on said drill-headto rotate and translate said shaft.

15. A drill head combining a casing; a first driven gear permanentlyjournaled in said casing and formed with a splined bore; a plurality ofbearing bosses (1d and 1) fixedly supported by said casing with theiraxes in alignment with the axis of said gear; a bearing provided by oneof said bosses; a first driven shaft (a) having one end splined withinsaid gear and its other end journaled in said bearing; a second shaft(b) having one end journaled in said bearing and'its other end in abearing provided by the other of said bearing bosses, said last namedbearing having an open end to permit withdrawal of said second shaft; asecond set of bearing bosses (1b, 1b and 1) provided by said casingand'having their axes parallel with the axes of the first namedbearings; a third shaft (b) having its opposite ends su ported in two ofsaid second set of bearing osses; one end of the last named shaft beingformed with a central bore affording a shaft bearing; a fourth shafthaving one end journaled in the bearing provided by said third shaft andits other end journaled in a bearing provided by one of the second setof bearing bosses, the last named bearing having an open end to permitwithdrawal of said fourth shaft therefrom;

a spindle driving sleeve journaled in said casing; a first set of speedchange gears mounted upon said first and third shafts; a second set ofspeed change ears supported by said third and second sha ts; and a thirdset of speed change gears mounted upon said secondtand fourth shafts andsaid spindle driving sleeve.

16. A drill-head combining a casing; a spindle rotatably journaledtherein; a driven bevel gear permanently journaled in said casing andformed with a central shaft-receiving aperture; a first set of bearingssupported by said casing and arranged with their axes in alignment withthe axis of said'bevel gear, one of said bearings extending through anouter Wall of said Casin first and third shafts, a and c, journale insaid bearings, one of said shaftshaving a splined driving connectionwith said bevel ear; a second set of aligned bearings provi ed by saidcasing, one of`the bearings of said second set extending through anouter wall of said casing; second and fourth shafts, b and d, jourynaledin said second set of bearings; primary and secondary sets of speedchange gears supported by the first, second and third shafts, a, b andc, adapted to transmit to the third shaft c a pluralit of speeds from asingle speed in the beve gear; a back-gear mechanism connecting thethird shaft c with a spindle; said first, second and third shafts, a, band c and the speed change gears carried thereby being removably securedin said casing, saidy shafts being withdrawable therefrom through thebearings extending through the outer wall of the casing, by axialmovement of saidvshafts.

In witness whereof, I hereunto subscribe my name.

DAVID C. KLAUSMEYER.

